A long-distance transportation of commercial heavy-duty trucks is mainly by transported by roads and railways. In the road transportation, two trucks even three trucks supporting-transport mode is mostly adopted due to factors such as fuel consumption and work force consumption of the road transportation. That is, one truck transports one or two trucks. This transportation mode may cause an over-limit and over-load problem, which is not safe and may cause a traffic accident. Meanwhile, under the limit of the transportation mode, the losses of the trucks caused by the long-distance driving may be an unnegligible problem when the products are transported to the customer. In another aspect, since the railway transportation has dedicated transportation tracks, losses of trucks during the railway transportation may be omitted. In addition, the railway transportation is not affected by factors such as traffic jam. In this case, goods can be transported to a destination rapidly and on time. However, the shape and size of the commercial heavy-duty truck is substantially fixed, and the trucks may go beyond the gauge of the railway when being loaded on the existing railway wagon for transportation. Therefore, a piggyback transportation mode is mostly adopted, in which a truck full of goods is transported for a long distance by a dedicated railway vehicle on the railway. A piggyback flat car of the dedicated railway vehicle has features of low floor loading surface and large concentrated load bearing, and one railway wagon can be loaded with one truck.